Chemical characterisation of grapevine waste and bioactivity on cancer cell lines

Grapevine waste is a potential source of bioactive phenolic compounds. Solvent extracts of stems, skins and defatted seeds from grapevine waste of both noble French and indigenous Maltese grapevine cultivars were studied. The individual parts were air dried and subjected to polar solvent extraction and concentrated. Grape seed oil was obtained from hexane defatted seeds. The crude concentrated polar fractions and grape seed oil were subjected to both quantitative and qualitative chemical analysis. The total phenolic and flavonoid content, together with the condensed tannins and their relative degree of polymerisation were determined. The total monomeric anthocyanin content was additionally determined for red cultivars' skin extracts. The antioxidant and radical scavenging activity of solvent extracts were determined using the non-cellular assays, DPPH and phosphomolybdenum assay. In general red skin and stem extracts had a higher phenolic, flavonoid and total antioxidant activity than white skin and stem extracts, with no significant difference between red and white cultivar seed extracts. Seed extracts had the highest phenolic and flavonoid content which were found to be significantly correlated to the antioxidant and antiradical activities. Skin and seed solvent extracts derived from the white indigenous cultivar Girgentina had a significantly lower degree of tannin polymerisation when compared to Chardonnay, whilst there was no significant difference in the amount of anthocyanin pigments between the indigenous red cultivar Gellewza and the French cultivar Syrah, but the individual pigment composition varied. Fermentation of skins and seeds during red wine production caused a significant loss in their phenolic, flavonoid and anthocyanin content which translated in a low antioxidant and radical scavenging activity. Apart from these changes in the hydrophilic fraction of grape seed extracts, fermentation also caused changes in the lipophilic fraction; it was observed that grape seed oils derived after fermentation had a higher concentration of lipid peroxides and secondary oxidation products. Selected polar solvent extracts were then tested for bioactive potential against human cancer cell lines; breast cancer MDA-MB-468 and two leukemic HL-60 and K562 cell lines, using modified formazan (MTT) and sulphorhodamine (SRB) assays. All extracts showed a dose and time dependent increase in bioactivity. In general K562 was found to be the least susceptible whilst MDA-MB-468 was the most susceptible. Morphological changes indicative of apoptosis were observed after 48 hour exposure. The highest bioactivity was for seed extracts which correlated with their high phenolic, flavonoid and antioxidant/radical scavenging activity, whilst the lowest bioactivity was recorded for white cultivar skin extracts and red cultivar skin extracts derived after fermentation. Although SRB assay had a slightly lower sensitivity when compared to MTT, it is the method of choice when testing novel phenolic compounds with a high reducing activity.

Grantor dc:publisher.institution

University of Malta

Year dc:date.issued

2014

• Cancer -- Nutritional aspects
• Bioactive compounds
• Fruit in human nutrition
• Grapes -- Malta
• Fruit -- Composition

Statement dc:rights

• info:eu-repo/semantics/restrictedAccess

Language dc:language.iso

en

Repository record dc:identifier.uri

https://www.um.edu.mt/library/oar/handle/123456789/64632

OAI identifier oai:identifier

oai:www.um.edu.mt:123456789/64632